(…) there are many ways in which a person’s reality model can malfunction and differ from the true external reality, giving rise…

“(…) there are many ways in which a person’s reality model can malfunction and differ from the true external reality, giving rise to illusions (incorrect perceptions of things that do exist in the external reality), omissions (nonperception of things that do exist in the external reality) and hallucinations (perceptions of things that don’t exist in the external reality).”

–Tegmark, Max.Our Mathematical Universe: My Quest for the Ultimate Nature of Reality. London: Penguin Books, 2014. (viacarvalhais)